Towards New Standards for Optimizing Corrugated Export Packaging

27th IAPRI Symposium on Packaging 2015

Towards New Standards for Optimizing

Corrugated Export Packaging

Thomas Trost

and Johan Alfthan

*_{Corresponding author Thomas Trost. Email: thomas.trost@innventia.com}

Keywords: corrugated, transport packaging, test methods, standards, packaging performance.

1 Introduction

The packaging industry and their customers seek to reduce costs and environmental impact of packaging. A general trend for packaging is that the amount of material is being reduced. The dominating material for transport packaging is corrugated board of various qualities and grammages. The average grammage in Europe has been reduced from 558 g/m² in 1997 [1] to 521 g/m² in 2013 [2]. Today the proportion of recycled fibres is also quite high in corrugated products. Of the total consumption of raw materials in 2013, 28 % was testliner [2]. This often means a lower quality of the corrugated board compared to the use of kraftliner made from virgin fibres.

While the material reduction continues, the packaging has to fulfil its duties. The products must be protected from humidity, dirt, shocks and vibrations. The exporting industry needs packaging that withstands transport and storage conditions during varying climates. Unfortunately, today there is often a gap between demands and applied protection, which leads to unnecessary damaged products, less goodwill and decreased competiveness. Earlier European studies have estimated very large direct and indirect damage costs already at low damage rates, e.g. Trost [3] and Braunmiller [4]. The problems are still there while the global market has become even more important today.

One reason for this damage exposed situation is lack of uniform performance standards and guidelines for transport packaging, i.e. mainly packages of corrugated board.

Abstract: A need for more efficient standards concerning transport packaging and export packaging

has been identified. The exporting industry today has problems finding the right transport packaging materials and solutions for different markets when it comes to performance. There is a lack of knowledge and guidelines to determine the properties of the box that are relevant and contribute to mechanical performance at different points of the distribution chain. In addition each industry branch faces different requirements and demands.

To meet the need, Innventia has started a study aiming towards uniform function standards to optimize corrugated board packaging. In this paper, an overview of the producers and brand owners requirements and demands on transport packaging will be presented. A range of test methods on paper, panel and box level will also be presented. An analysis will be given about their pros and cons. Further, it will be possible from this study to map out the direction for a focused development effort. There will be in-depth analyses, including:

• Current status, background and problem description with technical and economic implications • An overview of existing test methods and the need to change or modify them

For the globally active brand owner companies there are many problems and failings associated with corrugated board boxes. Each industry branch has different requirements and demands, but some common problems are:

• Corrugated board varies within the same quality, depending on where in the world it is bought. It means that the performance varies locally, despite the same nominal quality.

• There are today numerous test standards concerning different properties on paper (liner and fluting), panel or box level. Common mechanical test methods are ECT (Edge Crush Test), BCT (Box Compression Test), CMT (Corrugated Medium Test), bending stiffness, burst strength etc. There are little help or guidance on which properties are important, if they should be weighted together etc.

• The common test methods are described for laboratory standard climate which is 23 °C and 50 %RH. They do not cover what happens at other climates. Specifically, higher humidity is worse for the material but test methods are lacking. There are methods concerning water resistance such as Cobb test, but they do not necessary cover the needs for real life distribution.

• Some attempts have been done to weigh properties together, e.g. in EUPS (End Use Performance Standard) [5] or DIN 55 468 [6] but they only covers the needs partly. They miss the influence of humidity on the box performance. There are no standards for some relevant properties occurring during real cargo distribution, e.g. creep at cyclic climate.

• The requirements on transport packaging are also increasing. The demands on secondary packaging, i.e. the transport packaging, become more like the demands on the primary packaging, e.g. increased demands on good printing properties and high print quality. A study concerning these properties has been presented at IAPRI in 2013 by Trost et al. [7].

• The lack of a global performance standard means that many of the large packaging users, e.g. large product producing exporting companies, is at disadvantage and cannot easily specify their needs when purchasing packaging from corrugated board manufacturers.

The lack of relevant test methods for performance during distribution in many cases leads to the use of large safety factors, which themselves are uncertain. The safety factors are used in many different ways, which may create even more uncertainty.

Therefore it is a need for a global comprehensive performance standard or guidelines which give suitable quality of corrugated with lowest possible, but high enough, grammage.

Therefore a project called “Standards for optimizing corrugated board packaging for exporting industry” has been started. The aim of this project, which is a feasibility study, is to give the direction of further development of test methods for corrugated based on the real needs from industry. Figure 1 shows the activities in the project. The work consists of mapping of demands and mapping of existing standards followed by analysis and proposal for future work. Mapping of demands seen by the industry and mapping of existing standards will be described below, followed by an analysis with some results presented.

Figure 1: Simplified overview of presented activities in the project towards more useful test methods

for corrugated.

2 Methods

In order to map the demands from the goods producing industry a quite comprehensive questionnaire was developed, partly based on earlier work on systems for distribution quality by Trost [8] and work on goods classification by Björkman and Trost [9]. A number of interviews were held with packaging responsible persons at some large companies from different industrial sectors e.g. Duni, Ericsson, ESAB, Gambro Lundia, McNeil, SKF Mekan and Xylem Water Solutions.

The following topics were among those covered by the questionnaire:

• Types of damages, where they occur in the distribution chain, and how they are followed up • Damage frequency and statistics, influence on packaging development

• Test methods used on boxes and pallets

• Organization of packaging development, e.g. if development is performed in-house or by packaging supplier or consulting firms, and if the responsibility lies on product, division or central level in the organization

• The requirements on primary and secondary (transport) packaging and if they are evaluated together or independently of each other

• Use of packaging instructions; pallet pattern and marking

• Important environmental factors to protect against and how these are determined • Specification on corrugated board and boxes at purchase

• Quality control of delivered packaging material

The questionnaire and interviews were complemented by a workshop where problem areas and existing or possible solutions were identified.

The second activity was mapping and analysing the huge amount of European, American and global standard test methods on corrugated boxes and its constituents from organizations such as EN, ISO, IEC, ISTA, ASTM and Tappi. Identification of the most important test methods was made based on the outcome of the mapping of demands.

3 Results

The stresses encountered during transport are well known to be varying and often especially tough during loading and unloading, as noted in earlier in the literature, e.g. Bernad et al. [10]. Also many studies of stacked cargo on pallet have been performed, sometimes approached by modelling, e.g. Rouillard et al. [11].

One important aspect is that the packaging user wants performance of the whole box, but quite often the supplier talks about properties of the ingoing part, i.e. liner and fluting for corrugated board. Several problems with corrugated packaging today were identified. Poor pallet pattern and overhang on pallet causes many damages. Examples of this are shown in Figure 2. Stackability during transport and collapse cannot be easily predicted. Therefore many companies use very large safety factors. This problem has also increased with the number of sub-suppliers of packaging as well as products in non-European markets such as China and India. One example of the problems with uncertainties when dimensioning box strength is shown in Figure 2(d).

(a) (b) (c) (d)

Figure 2: Examples of poor pallet patterns and overhang causing damages: (a) Poorly secured cargo

on pallet and poorly secured pallets in the vehicle causes tilting and collapsed boxes; (b) Overhang on pallet and poor pallet pattern increases the risk for damage, and even collapsed load, during handling; (c) Poor pallet pattern and no securing will probably cause tilting and falling during transport; (d) A

too weak box causes tilting and collapse in warehouse.

Today there is a lack of specifications that works worldwide. There is a need for understandable and reasonable requirements, which also could be checked in a straightforward way by the purchasers. A common problem is that it is very hard today to compare corrugated board boxes performance from different suppliers, since data sheets are often given on paper or panel level. Also different producers focus on different properties, where they have their advantages. The interpretation of some specifications is sometimes unclear, e.g. meaning of a specific Cobb value. Many of the large retailers demand shelf ready packaging for fast moving consumer goods in order to save costs for unpacking

and expose the products better. The perforation on these boxes makes it more difficult to meet the transportation demands and the boxes may open before arrival to the retailer. A common problem is straps that deform the package, which may damage the product inside.

At the workshop several problem areas were identified, among them “Machine runnability” and “End use”. The problem areas “Logistics”, “Stackability and side impact” and “Climate” were identified as especially important due to the complexity and lack of standardised testing. The workshop outcomes on these areas are summarised in Figures 3–5.

The areas “Logistics” and “Stackability and side impact”, Figures 3–4, illustrates the complexity of the real world’s demands. Standards today give very little support to a user trying to make adequate specifications.

Figure 3: Examples of identified problems and possible solutions for “Logistics”.

Figure 4: Examples of identified problems and possible solutions for “Stackability and side impact”.

Figure 5 on the area “Climate” illustrates the climatic influence on the boxes. Creep is the gradual deformation due to long term loading. It becomes especially important at high or varying humidity. The possible solutions with modification of material properties obviously have to be made by the

material producers. Of course the problems presented in Figures 3–5 do not occur independently of each other. There is obviously always a climate also during logistics and stacking.

Figure 5: Examples of identified problems and possible solutions for “Climate”.

The standard test methods on corrugated board and boxes from EN, ISO, IEC, ISTA, ASTM and Tappi were mapped and analysed. These standards cover different aspects of the corrugated box and its constituents, such as test methods on the paper, board and box level but also so called rough handling performance protocols. The commonly used ASTM D 4169 [12] is an example of the last category.

In Figure 6, a schematic overview of some measured parameters on different levels is shown. It should be pointed out that many methods could be used both on paper level (liner or fluting for corrugated) and on panel level. Missing in Figure 6 are creep tests, because there are no standard test methods available today.

It was found among the users that on box level, BCT is regarded as most valuable. On the other hand there are not so many other box level methods to choose. Practically all companies use it, but still the standard method is only for laboratory climate of 23 °C and 50 %RH. A comprehensive literature survey about this method was recently presented by Frank [13]. This method misses the dramatic reduced stacking strength caused by even small stacking misalignment, which is common during distribution, e.g. Maltenfort [14], Meng [15] and Meng et al. [16]. Other questions are also how to relate the BCT value to real transportation conditions or vibration tests on a vibration table, and collapse due to creep.

Creep of corrugated boxes have been studied for a long time, but is yet not fully understood. Kellicutt and Landt [17] investigated the relation between applied load and time until collapse. They found that the time to failure of boxes under static loading decreased logarithmically as the dead load approached the box compression strength. Their study was performed at constant laboratory climate of 23 °C and 50 %RH.

Koning and Stern [18] studied the secondary creep rate and life time. They found that the life time was almost proportional to the inverse of the secondary creep rate.

One factor that is very important and demanding is varying air humidity, or even sometimes liquid water as rain. There is a general lack of methods for varying climate. All the common test methods are prescribed for laboratory standard climate of 23 °C and 50 %RH. However, in some countries products intended for installation are standing outdoors in their packaging for months making both climate and creep important.

When the humidity varies the creep situation is dramatically different as shown by e.g. Bronkhorst [19]. Bronkhorst could however find a relation between the average secondary creep rate and life time similar to the Koning and Stern [18].

Leake [20] and Leake and Wojcik [21] studied corrugated boxes stored for long time in warehouses with daily climatic variations. They found that a high-amylose starch based adhesive in the corrugated gave an improved performance in comparison to a standard corn starch adhesive. These changes of performance were not detected by standard compression tests (BCT).

For panel and paper properties, the following test methods were regarded important by users: • ECT (Edge Crush Test)

• FCT (Flat Crush Test) • Bending stiffness • Friction

• Printability

Another common test method is the Cobb test according to ISO 535 [22], which measures the water absorption on paper and board. It should be pointed out that this test only predicts the response of the material to a brief exposure to water. It gives no indication of the loss of strength to be expected following prolonged exposure to either water or high humidity (Wright et al. [23]). The method is also often used to determine printability. This is then based on company experience since the method is not in general relevant to the printing process, where the water exposure is less than a second compared to the minutes used in the test.

One complicating factor is that test methods on paper or panels show the properties before converting. It is well known that the converting process reduces the strength properties of the board to some extent by crushing the board (Batelka [24]). It has also been found that properties are lost in converting to different extent at different corrugating plants (Edholm [25]). Therefore Chalmers [26] introduced a new test method for corrugated based on torsional stiffness. Compared to conventional tests such as flat crush (FCT), thickness, edge crush (ECT) or box crush (BCT), MD torsional stiffness is according to Chalmers a more sensitive predictor of corrugated board performance in the corrugator and quantifier of the amount of damage incurred during the box conversion process.

Combined standards have been developed, i.e. standards which weigh together different properties to a number. One well known such standard is EUPS (End Use Performance Standard). This method is a first attempt to a global standard. Some factors that are missing in EUPS are influence of humidity, and design of the box. EUPS also favours liner properties rather than fluting properties, due to the mix of test methods used.

4 Conclusions

In order to reach real working methods for optimizing corrugated board packaging directions for further work has to be found. A feasibility study has thus been initiated. The first steps have been mapping of demands and of existing standards to find the state of the art and gaps between actual needs and available methods.

The challenge faced from the perspective of the user is to specify real box performance. Most methods consider material properties rather than box performance. For box performance, BCT is mostly used with safety factors to take requirements during transport and storage into account. These safety factors are based on experience and have large uncertainties. Safety factors are used in many different ways and combinations with unpredictable results. To summarize, it could be said that the uncertainty results in use of safety factors in many different ways, which creates even more uncertainty!

Some specific areas were found to be especially lacking: • uncertainties of loading during handling

• effects of vibrations, shocks and creep as well as design e.g. perforation on stacking strength • varying climate, and especially varying humidity

• long-time behaviour of boxes

• algorithms or equations going from panel level to box level, i.e. to include the conversion process In these areas both research and development of practical tools and guidelines for the designers and users are needed.

5 Acknowledgements

The authors express their thanks to the ÅForsk Foundation for their financial support. They also express their gratitude for fruitful discussions in the reference group for the project “Standards for optimizing corrugated board packaging for exporting industry”, namely P3G (The Packaging & Product Protection Group, an industry group managed by Innventia). The following companies participated in the project and are gratefully thanked for their input: aPak, BillerudKorsnäs, Duni, Ericsson, ESAB, Gambro Lundia, McNeil, Peterson Packaging, SKF Mekan, Tre Well Emballage and Xylem Water Solutions.

6 References

1. FEFCO Annual Statistics 2006. 2. FEFCO Annual Statistics 2013.

3. T. Trost (editor), 1998, “Identification of damage inducing mechanisms - Report on SRETS, Task no. 1.”, Packforsk Report no. 183.

4. U. Braunmiller (editor), 1999, “Source Reduction by European Testing Schedules (SRETS) – Final Report”, Packforsk Report no. 189.

5. EUPS, http://www.bfsv.de/eups/frameie.html, retrieved the 27th of April 2015.

6. DIN 55468: Packstoffe-Wellpappe. Teil 1: Anforderungen, Prüfung, 2013. Teil 2: Nassfest, Anforderungen, Prüfung, 2013 (in German).

7. T. Trost, P. Rättö and E. Blohm, 2013, “Packaging wear during transport simulation – comparison between laboratory coated samples and commercial samples”, 26th IAPRI Symposium on Packaging, Espoo, Finland, June 10-13.

8. T. Trost, 1992, “Description and analysis of distribution quality - Prestudy based on case studies”, Packforsk Report no. 154 (in Swedish).

9. H. Björkman and T. Trost, 1994, “Quality assurance of product, package and distribution – Interaction and systems for goods classification - a pilot study”, Packforsk Report no. 164 (in Swedish).

10. C. Bernad, A. Laspalas, D. González, E. Liarte and M. Jiménez, 2010, “Dynamic study of stacked packaging units by operational modal analysis”, Packaging Technology and Science, vol. 23, pp. 121-133.

11. V. Rouillard, M. Sek, and S. Crawford, 2004, “The dynamic behaviour of stacked shipping units during transport. Part 1: Model validation”, Packaging Technology and Science, vol. 17, pp. 237-247.

12. ASTM D4169-14: Standard Practice for Performance Testing of Shipping Containers and Systems. 13. B. Frank, 2014, “Corrugated Box Compression - A Literature Survey”, Packaging Technology and

Science, vol. 27, pp. 105–128.

14. G.G. Maltenfort, 1980, “Compression load distribution on corrugated boxes”, Paperboard Packaging, pp. 71-80.

15. G. Meng, 2007, “Experimental and numerical analysis of the load distribution in corrugated packaging system”, Master’s Thesis, KTH, Stockholm, Sweden.

16. G. Meng, T. Trost, and S. Östlund, 2007, “Stacking misalignment of corrugated boxes - a preliminary study”, 23rd IAPRI Symposium on Packaging, Windsor, UK, Sep. 3-5.

17. K.O. Kellicutt and E.F. Landt, 1951, “Safe stacking life of corrugated boxes”, Fibre Containers, vol. 36, no. 9, pp. 28-33.

18. J.W. Koning Jr. and R.K. Stern, 1977, “Long-term creep in corrugated fiberboard containers”, Tappi, vol. 60, no. 12, pp. 128-131.

19. C.A. Bronkhorst, 1997, “Towards a more mechanistic understanding of corrugated container creep deformation behaviour”, Journal of Pulp and Paper Science, vol. 23, no. 4, pp. 174-181. 20. C.H. Leake, 1988, “Measuring corrugated box performance”, Tappi Journal, Oct., pp. 71-75. 21. C.H. Leake and R. Wojcik, 1989, “Influence of the combining adhesive on box performance”,

Tappi Journal, Aug., pp. 61-65.